SLLSFV1 March 2025 MCF8329A-Q1
PRODUCTION DATA
Selecting an appropriate gate drive current is essential when turning on or off power MOSFETs gates to switch motor current. The amount of gate drive current and input capacitance of the MOSFETs determines the drain-to-source voltage slew rate (VDS). Gate drive current can be sourced from GVDD into the MOSFET gate (ISOURCE) or sunk from the MOSFET gate into SHx or LSS (ISINK).
Using too high of a gate drive current can turn on MOSFETs too quickly which may cause excessive ringing, dV/dt coupling, or cross-conduction from switching large amounts of current. If parasitic inductances and capacitances exist in the system, voltage spiking or ringing may occur which can damage the MOSFETs or the MCF8329A-Q1 device.
On the other hand, using too low of a gate drive current causes long VDS slew rates. Turning on the MOSFETs too slowly may heat up the MOSFETs due to RDS,on switching losses.
The relationship between gate drive current IGATE, MOSFET gate-to-drain charge QGD, and VDS slew rate switching time trise,fall are described by the following equations:
It is recommend to evaluate at lower gate drive currents and increase gate drive current settings to avoid damage from unintended operation during initial evaluation.